Advanced detections for deciphering the catalytic reaction behaviors of lithium-sulfur batteries

Lithium-sulfur batteries (LSBs) have engendered extensive research attention due to their outstanding theoretical capacity (1672 mA h g -1 ), energy density (2600 Wh kg -1 ) as well as the low cost of sulfur. Nevertheless, the shuttle effect as well as the retarded sulfur reaction kinetics have become one of the most fatal issues. In response, the use of electrocatalysts in LSBs has been confirmed as an effective strategy thus far. However, the unclear electrocatalytic mechanism increases the difficulties of understanding the practical functions of electrocatalysts and constructing advanced cathodes toward commercially viable LSBs. In this respect, recent years have witnessed many fruitful advances in deciphering the reaction mechanism of LSBs by ex -situ and in -situ characterization techniques. In the past several years, the optical spectroscopy, time of flight secondary ion mass spectroscopy, synchrotron radiation -based X-ray, neutron analysis techniques, etc., have shown great promise to disclose the underlying electrocatalytic mechanism of promotors for the Li 2 S nucleation and decomposition reactions, considerably contributing to the latest advancements of LSB system research. In this tutorial review, we provide a systematic summary of the state-of-the-art electrocatalytic mechanism investigations by virtue of the emerging advanced detection techniques aimed at propelling the theoretical and practical research of LSBs.